I'm not too sure but I think LATAM devices have a certain limitation when it comes to flashing other region ROMs or any other ROMS for that matter. Try using Kholk's alternative method of flashing using the cmd prompt. If that doesn't work as well, then I guess you're stuck.

so that means I can only flash the ROM without signature or sth like that?

'cause right now, I can't update to cook ICS room via safetrap, it requires EU system version

Not exactly. You can only flash roms signed to your device, or nandroid backups - wich doens't update system kernell, radio, but apps - Even with kholk alternative to trick RSD lite signature verification will not work when flashing. It's a locked bootloader issue actualy. Sorry

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